1. Field of the Invention
The present invention concerns a machine for the continuous manufacture of circular waveguide formed by a wound helix of insulated round metal conductor, with adjacent turns of the helix being in peripheral contact.
If a circular guide carrying the TE.sub.01 mode has a perfect circular geometry, then the propagation of the TE.sub.01 mode is undisturbed provided the guide walls are made of a homogeneous conductor. One of the most attractive features of such a guide is its low attenuation: the larger the pipe diameter and the higher the frequency, the lower the guide attenuation. Unfortunately the TE.sub.01 mode is degenerate with the TM.sub.11 mode and it can be shown that imperfection of the circular geometry brings about a coupling between the two modes, with a consequent loss of power; thus low attenuation is lost.
2. Description of the Prior Art
Machines for manufacturing an indefinite length of circular waveguide by winding an insulated metal wire with adjacent turns in peripheral contact are known in the prior art.
In a first kind of machines, a typical example of which is disclosed in British Pat. No. 887,063 of Mar. 8, 1957, the wire is wound on a rotating spindle so that adjacent turns contact therewith edge-to-edge and the winding is left on the spindle during a time just sufficient for making it rigid and armoring it. The incoming turns are progressively pushed along the spindle by rotating rollers in order to define and make stationary the location of the plane of the first turn of the helix along the spindle. The helix is impregnated with a thermosetting resin or the like and, at a point of the waveguide winding where it has become solid due to the setting of the resin, the diameter of the spindle is decreased either progressively or steppedly or the spindle is cooled with respect to the winding for allowing the winding to be readily removed. If the spindle is mounted in an overhanging relation in respect to the winding, it is possible with these machines to manufacture a circular waveguide in a continuous operation. However these wire winding machines with decreasing spindle diameter do not allow manufacture of large lengths of waveguide per unit of time due to the operating requirement that the waveguide winding must be solidified at the point where the spindle diameter changes to limit the rate of manufacture.
In other machines, a typical example of which is disclosed in French Pat. No. 1,604,891 of Apr. 17, 1972, the spindle is not stepped in diameter and is either rotative or stationary and the insulated conductor wire is wound onto the spindle by means of a rotating carriage carrying the wire supply reel. These rotating carridge winding machines do not lend themselves readily to continuous operation due to the necessity of frequent changing of the empty reels in the rotating carriage and also due to the fact that the moment of inertia of the carriage varies as the reel empties which results in troublesome variation of the wire tension and results in irregularities in winding.